feat(models): AiderEventIn + AiderBatchIn pydantic schemas

- Implement aider-watch v2 event schema with 7 event types
- Enforce timezone-aware timestamps via field_validator
- Batch schema supports up to 50 events per request
- Frozen + forbid extra fields (defensive engineering)
- Fix broken src.* imports in models package (incident.py, __init__.py)

Task A3 complete: 7/7 tests passing

apps/api/src/models/incident.py

@@ -28,7 +28,7 @@ from uuid import UUID, uuid4
 from pydantic import BaseModel, Field, field_validator
 
 # 復用現有模型 (避免重複定義)
-from src.models.approval import BlastRadius
+from apps.api.src.models.approval import BlastRadius
 
 # =============================================================================
 # Incident 專用 Enums